Delawna Berran-Lett, the mother of Ky'heir and Dy'heir Arthur, waived her right to a preliminary hearing Wednesday. Allegheny County police said she's charged with involuntary manslaughter, reckless endangerment and endangering the welfare of a child.

"Her world is completely torn upside down. She's not eating. She's not sleeping at night. She's having a lot of trouble," defense attorney Blaine Jones said.

County fire marshals found that the fatal house fire on the afternoon of Jan. 4 began in a stove, according to District Attorney Stephen Zappala. The medical examiner said one twin died of burns and smoke inhalation, and the other boy suffered smoke inhalation and carbon monoxide poisoning.

According to family members, the mother said she briefly left the house on Rebecca Street for a few minutes to find her teenage daughter, then returned to see the home on fire. But Zappala said the investigation by county homicide detectives shows that the mother was really gone for almost an hour.

Zappala said the woman was angry because some marijuana was missing from her purse, and she suspected her daughter took it, so when the girl didn't come off her school bus that day, she went out in search of the teen.

Defense attorney Charles Gallo said Berran-Lett's decision to leave the house was a "lapse in judgement."

"Leaving the house shouldn't express her feelings in how she felt about the kids, in whether she was a good mother or bad mother," he said.

When asked why she left the children alone, Gallo told reporters, "I don't want to get into the facts or get into a defense and try the case in the media."

Information from witness interviews indicated that the boys sometimes operated the stove themselves and cooked their own food, Zappala said.

The home is a Section 8 property, and the stove had been "red tagged," according to Zappala. He said it's not tagged "in the sense that work needed to be done on the unit," but he does want to investigate further.

"We want to know more about what happens when a utility company comes in and says, hey, you've got to take a look at the stuff that you're supposed to be providing people when they become a tenant in your home," Zappala said.